Out of a wide range of both pharmacological and psychosocial interventions for substance use disorders in adolescents comes a potentially valuable piece of the treatment puzzle, a piece that can be found among the many over-the-counter supplements in drug and grocery stores. The potential value of N-acetylcysteine (NAC), an inexpensive supplement, is somewhat reassuring given the increasing concern about the misuse and abuse of prescription and over-the-counter drugs by adolescents (1). Gray and colleagues (2) report in this issue an 8-week double-blind randomized placebo-controlled trial, in which 116 cannabis-dependent adolescents ages 15–21 received NAC or placebo twice daily, each added to a contingency management intervention and brief weekly cessation counseling. Adolescents receiving NAC had more than twice the odds, when compared with placebo participants, of having negative urine cannabinoid tests during treatment. As the authors note, this is the first well-controlled pharmacotherapy study for cannabis dependence to show a positive primary cessation outcome (as opposed to decreased use) in an intent-to-treat analysis. In a previous open-label study of NAC in 24 dependent marijuana users by Gray and colleagues (3), users reported reductions in days per week of use and “number of hits,” but urine cannabinoid measures did not significantly change over the treatment period. In addition to decreased overall use, reductions in reported compulsivity, emotionality, and purposefulness regarding marijuana use were reported, reflecting an improvement in three of the four domains of the Marijuana Craving Questionnaire.